According to DE4110195A1, a valve timing control apparatus includes a rotary member, which is rotated in conjunction with a crankshaft, and a rotary member, which is rotated in conjunction with a camshaft. The rotary members are connected by a planetary gear mechanism so as to control a valve timing on the basis of the relative phase between the rotary members.
A valve timing control apparatus having such a structure includes first to fourth gear portions. The third gear portion and the fourth gear portion are unitarily provided with a planetary rotary member. The third and fourth gear portions are eccentrically meshed respectively with the first gear portion, which is provided in the interlocking rotary member of the crankshaft, and the second gear portion, which is provided in the interlocking rotary member of the camshaft. Thus, a large reduction ratio can be attained with a compact structure, so that the valve timing control apparatus can be suitably mounted in an internal combustion engine.
In the above valve timing control apparatus, backlash ascribable to a manufacturing tolerance or the like inevitably exist at the meshed portion between the first gear portion and the third gear portion and the meshed portion between the second gear portion and the fourth gear portion. Such a backlash may cause an abnormal sound or damage ascribable to the collision between the gear portions. Accordingly, the backlash is preferably eliminated. However, the third gear portion and the fourth gear portion are unitarily provided in the planetary rotary member. Accordingly, it has been difficult to simultaneously eliminate the backlash at both the meshed portion between the first gear portion and the third gear portion and the meshed portion between the second gear portion and the fourth gear portion.